Phat Tran · Senior Mobile Engineer
Six years of production mobile apps across banking, financial services, digital health, and e-commerce. Right now I'm building an e-wallet at VinSmart Future in Ho Chi Minh City.
E-Wallet
$24,580
+12%Balance
$8,420
+8%Savings
Payment Sent
2m ago
Top Up
1h ago
Coffee Shop
3h ago
About
I'm Phat Tran. Online I go by VamoSs. Most of my six years in mobile development have been spent on apps where a bug costs someone money: consumer lending, digital banking, e-wallets, with detours into digital health and e-commerce. The project I'm proudest of is FE Online 2.0, a lending and banking super app I led at FE Credit that serves more than 3 million people.
These days I'm at VinSmart Future building a new e-wallet. The job, as I see it: take slow, complicated financial operations and make them feel like nothing. In practice that means architecture work, profiling, and a lot of testing, which happens to be the part I enjoy most.
Outside of work I maintain a few open-source packages and write here about mobile performance, CI/CD, and whatever bit me most recently on the job.
6+
Years of mobile
10+
Apps shipped
10M+
Combined downloads
30+
Open-source PRs
Experience
Building a new e-wallet super app. I own the app's centralized payment flow: one path that every transaction goes through, so new features plug into payments instead of rebuilding them. I also look after features on both the CREDIT and non-CREDIT side.
Elfie is a health and rewards app with over 1.5 million users. I spent most of my year on performance: faster cold and warm starts, and far fewer OOM and ANR crashes after a lot of profiling and widget-rebuild work. I also owned the Biological Age feature end to end and contributed to Sleep, Cycle, and Skin Health.
Project lead for FE Online 2.0, a Flutter super app with more than 3 million users covering loans, digital banking, and BNPL. I directed the e-KYC, SmartOTP, NFC, and payment gateway integrations, set up CI/CD on Codemagic that cut deployment time in half, and mentored the junior developers on the team.
Built core features for OctoSells and OctoPOS, which give 500+ sellers one place to run their Shopee, Lazada, Tiki, and TikTok shops. I implemented the real-time chat between sellers and customers and a warehouse management module.
Built an app that lets parents follow their children's progress at school in real time and message their teachers directly.
Blog
Notes on Flutter and mobile development. Mostly things I had to figure out the hard way at work.
Push your Flutter app to the absolute limit. Learn how to achieve zero-overhead native communication using FFI and Rust, and when you should (and shouldn’t) use it.
Stop Out-Of-Memory (OOM) crashes and reduce your download size. Learn the critical rules of Image Caching, hunting Memory Leaks, and analyzing your final build size.
Stop freezing your app during heavy data processing. Learn the difference between async/await and true concurrency, and how to use Isolate.run() to keep your UI silky smooth.
How Flutter actually decides what rebuilds, why extracting widgets into classes does not speed anything up by itself, and the techniques that measurably do: const, the child parameter, RepaintBoundary, and scoped state.
Measure first, optimize later. Stop guessing why your Flutter banking app is lagging and learn how to use DevTools, Profile Mode, and the Performance Overlay to find the real bottlenecks.
Where RxDart earned its place in a finance app: debounced beneficiary search, one balance built from three streams, and stopping duplicate transfers.
Contact
If you'd like to talk about a project, a role, or just Flutter, write me. Everything sent through this form lands in my inbox.
Location
Ho Chi Minh City, VN